A method, device, equipment and storage medium for designing a multi-stage turbo refrigeration cycle

Abstract

This disclosure provides a multi-stage turbine refrigeration cycle design method, apparatus, equipment, and storage medium. The method includes iterative optimization of the final-stage turbine based on basic boundary conditions and a preset parameter configuration method to determine the operating point of the final-stage turbine; proceeding step-by-step recursion based on the operating point of the final-stage turbine to determine new turbine operating points, obtaining the total number of turbine stages and the total set of turbine operating points; configuring the heat exchangers in the cryogenic temperature zone turbine section; verifying the total set of turbine operating points based on the configuration results; outputting a set of turbine operating points to be used based on the verification results; comparing the outlet pressure of the final-stage turbine operating point in the set of turbine operating points to be used with a preset critical pressure; refining the set of turbine operating points to be used based on the comparison results; determining the overall turbine operating point set; and outputting the refrigeration process parameters. This forms a multi-stage turbine configuration optimization method that balances efficiency and cost, and constructs an engineering-correctable multi-stage turbine parameter recursion process.

Description

Technical Field

[0001] This disclosure relates to the field of cryogenic refrigeration technology, and in particular to a design method, apparatus, equipment and storage medium for a multi-stage turbine refrigeration cycle. Background Technology

[0002] Large-capacity liquid helium temperature refrigeration systems are core infrastructure supporting the operation of large-scale scientific facilities such as superconducting devices, ultra-large-scale quantum computing, nuclear fusion engineering, and particle accelerators. (Breton) Joule Thomson (Brayton) The JT hybrid refrigeration cycle, also known as the Claude cycle, has become the mainstream technology for achieving high-power, high-capacity liquid helium refrigeration due to its efficient energy cascade utilization characteristics.

[0003] Currently, the process design of large-capacity liquid helium refrigeration systems largely relies on engineering experience, typically employing open-loop, single-step design methods. A step-by-step temperature and pressure matching optimization approach based on Carnot step sizes has not yet been established, and a systematic and iterative optimization process is lacking. For example, the determination of critical temperature points, the distribution of enthalpy drop in each turbine stage, the setting of intermediate pressures, and the control of heat exchanger temperature differences are often based on empirical values ​​or simplified models, failing to establish a global optimization system. Furthermore, during the design process, there is insufficient consideration of the correction to the actual expansion process, the coordinated verification of multi-stage turbines and heat exchangers, and the systematic consideration of process robustness. Summary of the Invention

[0004] To solve the above-mentioned technical problems, or at least partially solve them, this disclosure provides a multi-stage turbine refrigeration cycle design method, apparatus, equipment, and storage medium.

[0005] This disclosure provides a method for designing a multi-stage turbine refrigeration cycle, the method comprising: Based on user requirements and compressor parameters, basic boundary conditions are determined. Based on the basic boundary conditions and preset parameter configuration method, the final stage turbine is iteratively optimized to determine the operating point of the final stage turbine. The operating point of the final stage turbine includes the outlet temperature, the inlet temperature and the final stage turbine setting framework. Based on the operating point of the final turbine stage, calculate the initial compressor flow rate and initial total theoretical work of each stage, and proceed step by step in the direction of increasing temperature to determine the new turbine operating point. If the power consumption reduction benefit corresponding to the new turbine operating point meets the first preset condition, output the total number of turbine stages and the total set of turbine operating points. The heat exchangers of the turbine section in the cryogenic temperature zone are configured based on the total number of turbine stages and the total set of turbine operating points. The total set of turbine operating points is verified according to the configuration results. If the verification results meet the second preset condition, the set of turbine operating points to be used is output. The outlet pressure of the last-stage turbine operating point in the set of turbine operating points to be used is compared with the preset critical pressure. Based on the comparison result, the main turbine operating point is determined and added to the set of turbine operating points to be used to obtain the overall turbine operating point set. The refrigeration process parameters are determined and output based on the overall turbine operating point set.

[0006] The method provided in this disclosure, which determines basic boundary conditions based on user requirements and compressor parameters, and iteratively optimizes the final-stage turbine based on the basic boundary conditions and a preset parameter configuration method to determine the operating point of the final-stage turbine, includes: The first iteration condition is determined based on the aforementioned basic boundary conditions; Based on the first iteration condition and the preset first parameter configuration method, several initial temperatures are assumed and iterated. Based on the preset accuracy condition, the outlet temperature of the final turbine is determined from the iteration results of all initial temperatures. The inlet and outlet pressures of the final stage turbine are determined based on the basic boundary conditions. The final stage turbine configuration framework and the inlet temperature of the final stage turbine are determined by back calculation based on the inlet and outlet pressures of the final stage turbine, the outlet temperature of the final stage turbine and the helium adiabatic index, using the preset second parameter configuration method. The operating point of the final stage turbine is determined by combining the outlet temperature, the final stage turbine configuration, and the inlet temperature.

[0007] The method provided in this disclosure, which assumes several initial temperatures based on the first iteration condition and a preset first parameter configuration method and iterates through them, determines the outlet temperature of the final stage turbine from the iteration results of all initial temperatures based on a preset accuracy condition, includes: Based on the first iteration condition and the preset first parameter configuration method, several initial temperatures are assumed. Based on the first iteration condition and the preset Joule-Thomson throttling process, the temperature calculation point corresponding to each initial temperature is determined, and the required mass flow rate of the Joule-Thomson throttling path at the corresponding temperature calculation point is obtained. The total compressor flow rate at the corresponding initial temperature is obtained by summing the mass flow rates at all temperature calculation points corresponding to each initial temperature. Based on all initial temperatures and the corresponding total flow rate of the compressor, a relationship curve is plotted. Based on preset screening conditions, the minimum value is optimized in the relationship curve to determine the candidate outlet temperature. The accuracy of the candidate outlet temperature is determined according to the preset accuracy condition. If the accuracy of the candidate outlet temperature meets the preset accuracy condition, the candidate outlet temperature is output as the outlet temperature of the final stage turbine. If the accuracy of the candidate outlet temperature does not meet the preset accuracy condition, then a second iteration condition is determined based on the basic boundary condition, and a new initial temperature is assumed based on the second iteration condition and the candidate outlet temperature to obtain a new candidate outlet temperature, until a candidate outlet temperature meets the preset accuracy condition, and the candidate outlet temperature is output as the outlet temperature of the final stage turbine.

[0008] The method provided in this disclosure, which determines the inlet and outlet pressures of the final stage turbine based on the basic boundary conditions, and determines the final stage turbine setup structure and inlet temperature based on a preset second parameter configuration method using the final stage turbine inlet and outlet pressures, the final stage turbine outlet temperature, and the helium adiabatic index, includes: The ideal inlet temperature of the turbine is calculated based on the inlet and outlet pressures of the final stage turbine, the outlet temperature of the final stage turbine, and the helium adiabatic index. The ideal inlet specific enthalpy is obtained by referring to the preset property table based on the ideal inlet temperature of the turbine and the inlet pressure of the final stage turbine. The inlet and outlet specific enthalpy of the turbine is obtained by referring to the preset property table based on the inlet and outlet pressures and outlet temperature of the final turbine. The ideal specific enthalpy drop is obtained by subtracting the ideal specific enthalpy from the turbine inlet and outlet specific enthalpy. The maximum ideal speed of the expander is then calculated based on the ideal specific enthalpy drop. If either the maximum ideal speed of the expander or the ideal specific enthalpy drop exceeds the preset engineering feasible range for a single-stage turbine, the final-stage turbine is split. Based on the splitting result, the ideal turbine inlet temperature, the maximum ideal speed of the expander, and the ideal specific enthalpy drop are recalculated until both the maximum ideal speed of the expander and the ideal specific enthalpy drop are within the preset engineering feasible range for a single-stage turbine. If so, the splitting result is deemed valid, and a final-stage turbine configuration framework including the number of turbine stages and the ideal specific enthalpy drop is determined based on the splitting result. The polytropic index is determined based on the initial number of turbine stages in the final turbine configuration, and the ideal inlet temperature of the final turbine is calculated based on the polytropic index.

[0009] The method provided in this disclosure calculates the initial compressor flow rate and initial total theoretical work of each stage based on the operating point of the final stage turbine, and proceeds step-by-step in the direction of increasing temperature to determine the new turbine operating point. If the power consumption reduction benefit corresponding to the new turbine operating point meets a first preset condition, the method outputs the total number of turbine stages and the total set of turbine operating points, including: Calculate the initial compressor flow rate of each stage based on the operating point of the final turbine, and sum the initial total theoretical work by summing the flow rates of all initial compressors. The inlet temperature of the last stage turbine operating point is used as the outlet temperature of the new turbine. The inlet temperature of the new turbine and the new turbine setting structure are determined according to the preset second parameter configuration method in the preset parameter configuration method. The operating point of the new turbine is determined based on the outlet temperature of the new turbine, the inlet temperature of the new turbine, and the new turbine configuration. Based on the newly added turbine operating point and the final stage turbine operating point, the flow rate and total theoretical work of each stage compressor are recalculated to obtain the recalculation results. Based on the recalculation results, the power consumption reduction benefit obtained due to the newly added turbine operating point is determined, and the power consumption reduction benefit is compared with the first preset condition. The first preset condition includes a preset percentage threshold and a preset liquid nitrogen temperature; If the power consumption reduction benefit is higher than the preset percentage threshold, the inlet temperature of the new turbine operating point is compared with the preset liquid nitrogen temperature. If the inlet temperature of the new turbine operating point is higher than the preset liquid nitrogen temperature, the stage addition is stopped, and the total number of turbine stages is determined based on the last turbine operating point and the new turbine operating point. If the inlet temperature of the new turbine operating point is lower than the preset liquid nitrogen temperature, the inlet temperature of the new turbine operating point is used as the outlet temperature for continuing to add turbines, and the process is repeated to obtain the new turbine operating points. The power consumption reduction benefit is then recalculated and compared. If the power consumption reduction benefit is lower than the preset percentage threshold, the total number of turbine stages is determined based on the operating point of the final turbine stage and the operating point of the newly added turbine stage. The preset percentage threshold is the percentage decrease in the total theoretical work in the recalculated result relative to the initial total theoretical work; Output the total number of turbine stages and the total set of turbine operating points, wherein the total set of turbine operating points includes all newly added turbine operating points and the operating point of the final turbine stage.

[0010] The method provided in this disclosure configures the heat exchanger in the cryogenic temperature zone turbine section based on the total number of turbine stages and the total turbine operating point set, verifies the total turbine operating point set according to the configuration result, and outputs the turbine operating point set to be used if the verification result meets a second preset condition, including: The heat exchangers in the cryogenic temperature zone turbine section are configured based on the total number of turbine stages and the total set of turbine operating points. Based on the turbine parameters corresponding to each turbine operating point in the total turbine operating point set, the minimum heat transfer temperature difference of each heat exchanger in the configuration result is calculated. The total turbine operating point set is verified according to the minimum heat transfer temperature difference. Based on the verification result, heat exchangers that do not meet the second preset condition are determined, and a list of heat exchangers to be adjusted is obtained. Calculate the temperature difference margin based on the minimum heat transfer temperature difference and the second preset condition, determine the correction target value of the list of heat exchangers to be adjusted based on the temperature difference margin, calculate the supplementary operating point based on the correction target value using the preset parameter configuration method, adjust the configuration of the heat exchangers in the cryogenic temperature zone turbine section based on the supplementary operating point, and add the supplementary operating point to the total turbine operating point set. Based on the turbine parameters corresponding to the supplemented total turbine operating point set, the minimum heat transfer temperature difference of each heat exchanger in the configuration adjustment result is calculated. If there are still heat exchangers that do not meet the second preset condition, a second supplement is performed until all heat exchangers meet the second preset condition. The corresponding total turbine operating point set is then output as the turbine operating point set to be used.

[0011] The method provided in this disclosure compares the outlet pressure of the last-stage turbine operating point in the set of turbine operating points to be used with a preset critical pressure, determines the main turbine operating point based on the comparison result, and adds the main turbine operating point to the set of turbine operating points to be used, thereby obtaining a complete turbine operating point set. Based on the complete turbine operating point set, refrigeration process parameters are determined and output, including: Extract the outlet pressure of the last stage turbine operating point in the set of turbine operating points to be used, compare the outlet pressure with the preset critical pressure, if the outlet pressure is less than or equal to the preset critical pressure, then there is no need to add a main turbine operating point. Then, organize the inlet and outlet temperatures, pressures, flow rates and all heat exchanger temperature nodes of each turbine operating point in the set of turbine operating points to be used to obtain the refrigeration process parameters. If the outlet pressure is greater than the preset critical pressure, it is determined that a new main road turbine operating point needs to be added. The outlet pressure corresponding to the main road turbine operating point is compared with the preset critical pressure. If the outlet pressure is greater than the preset critical pressure, it is determined that a new main road turbine operating point needs to be added. This process continues until the outlet pressure corresponding to the newly added main road turbine operating point is less than or equal to the preset critical pressure, at which point the addition of a new main road turbine operating point is stopped.

[0012] This disclosure also provides a multi-stage turbine refrigeration cycle design device, the device comprising: The iteration module is used to determine the basic boundary conditions according to user requirements and compressor parameters, and to perform iterative optimization of the final stage turbine based on the basic boundary conditions and the preset parameter configuration method to determine the operating point of the final stage turbine. The operating point of the final stage turbine includes the outlet temperature, the inlet temperature and the final stage turbine setting framework. The recursive module is used to calculate the initial compressor flow rate and initial total theoretical work of each stage based on the operating point of the final stage turbine, and proceeds to the next stage in the direction of increasing temperature to determine the new turbine operating point. If the power consumption reduction benefit corresponding to the new turbine operating point meets the first preset condition, the module outputs the total number of turbine stages and the total set of turbine operating points. The configuration module is used to configure the heat exchanger of the turbine section in the cryogenic temperature zone based on the total number of turbine stages and the total turbine operating point set, and to verify the total turbine operating point set according to the configuration result. If the verification result meets the second preset condition, the module outputs the turbine operating point set to be used. The output module is used to compare the outlet pressure of the last stage turbine operating point in the set of turbine operating points to be used with the preset critical pressure, determine the main turbine operating point based on the comparison result, and add the main turbine operating point to the set of turbine operating points to be used to obtain the overall turbine operating point set. The refrigeration process parameters are determined and output based on the overall turbine operating point set.

[0013] The iterative module in the apparatus provided in this disclosure is specifically used for: The first iteration condition is determined based on the aforementioned basic boundary conditions; Based on the first iteration condition and the preset first parameter configuration method, several initial temperatures are assumed and iterated. Based on the preset accuracy condition, the outlet temperature of the final turbine is determined from the iteration results of all initial temperatures. The inlet and outlet pressures of the final stage turbine are determined based on the basic boundary conditions. The final stage turbine configuration framework and the inlet temperature of the final stage turbine are determined by back calculation based on the inlet and outlet pressures of the final stage turbine, the outlet temperature of the final stage turbine and the helium adiabatic index, using the preset second parameter configuration method. The operating point of the final stage turbine is determined by combining the outlet temperature, the final stage turbine configuration, and the inlet temperature.

[0014] The iterative module in the apparatus provided in this disclosure is specifically used for: Based on the first iteration condition and the preset first parameter configuration method, several initial temperatures are assumed. Based on the first iteration condition and the preset Joule-Thomson throttling process, the temperature calculation point corresponding to each initial temperature is determined, and the required mass flow rate of the Joule-Thomson throttling path at the corresponding temperature calculation point is obtained. The total compressor flow rate at the corresponding initial temperature is obtained by summing the mass flow rates at all temperature calculation points corresponding to each initial temperature. Based on all initial temperatures and the corresponding total flow rate of the compressor, a relationship curve is plotted. Based on preset screening conditions, the minimum value is optimized in the relationship curve to determine the candidate outlet temperature. The accuracy of the candidate outlet temperature is determined according to the preset accuracy condition. If the accuracy of the candidate outlet temperature meets the preset accuracy condition, the candidate outlet temperature is output as the outlet temperature of the final stage turbine. If the accuracy of the candidate outlet temperature does not meet the preset accuracy condition, then a second iteration condition is determined based on the basic boundary condition, and a new initial temperature is assumed based on the second iteration condition and the candidate outlet temperature to obtain a new candidate outlet temperature, until a candidate outlet temperature meets the preset accuracy condition, and the candidate outlet temperature is output as the outlet temperature of the final stage turbine.

[0015] The iterative module in the apparatus provided in this disclosure is specifically used for: The ideal inlet temperature of the turbine is calculated based on the inlet and outlet pressures of the final stage turbine, the outlet temperature of the final stage turbine, and the helium adiabatic index. The ideal inlet specific enthalpy is obtained by referring to the preset property table based on the ideal inlet temperature of the turbine and the inlet pressure of the final stage turbine. The inlet and outlet specific enthalpy of the turbine is obtained by referring to the preset property table based on the inlet and outlet pressures and outlet temperature of the final turbine. The ideal specific enthalpy drop is obtained by subtracting the ideal specific enthalpy from the turbine inlet and outlet specific enthalpy. The maximum ideal speed of the expander is then calculated based on the ideal specific enthalpy drop. If either the maximum ideal speed of the expander or the ideal specific enthalpy drop exceeds the preset engineering feasible range for a single-stage turbine, the final-stage turbine is split. Based on the splitting result, the ideal turbine inlet temperature, the maximum ideal speed of the expander, and the ideal specific enthalpy drop are recalculated until both the maximum ideal speed of the expander and the ideal specific enthalpy drop are within the preset engineering feasible range for a single-stage turbine. If so, the splitting result is deemed valid, and a final-stage turbine configuration framework including the number of turbine stages and the ideal specific enthalpy drop is determined based on the splitting result. The polytropic index is determined based on the initial number of turbine stages in the final turbine configuration, and the ideal inlet temperature of the final turbine is calculated based on the polytropic index.

[0016] The apparatus provided in this disclosure, wherein the recursive module is specifically used for: Calculate the initial compressor flow rate of each stage based on the operating point of the final turbine, and sum the initial total theoretical work by summing the flow rates of all initial compressors. The inlet temperature of the last stage turbine operating point is used as the outlet temperature of the new turbine. The inlet temperature of the new turbine and the new turbine setting structure are determined according to the preset second parameter configuration method in the preset parameter configuration method. The operating point of the new turbine is determined based on the outlet temperature of the new turbine, the inlet temperature of the new turbine, and the new turbine configuration. Based on the newly added turbine operating point and the final stage turbine operating point, the flow rate and total theoretical work of each stage compressor are recalculated to obtain the recalculation results. Based on the recalculation results, the power consumption reduction benefit obtained due to the newly added turbine operating point is determined, and the power consumption reduction benefit is compared with the first preset condition. The first preset condition includes a preset percentage threshold and a preset liquid nitrogen temperature; If the power consumption reduction benefit is higher than the preset percentage threshold, the inlet temperature of the new turbine operating point is compared with the preset liquid nitrogen temperature. If the inlet temperature of the new turbine operating point is higher than the preset liquid nitrogen temperature, the stage addition is stopped, and the total number of turbine stages is determined based on the last turbine operating point and the new turbine operating point. If the inlet temperature of the new turbine operating point is lower than the preset liquid nitrogen temperature, the inlet temperature of the new turbine operating point is used as the outlet temperature for continuing to add turbines, and the process is repeated to obtain the new turbine operating points. The power consumption reduction benefit is then recalculated and compared. If the power consumption reduction benefit is lower than the preset percentage threshold, the total number of turbine stages is determined based on the operating point of the final turbine stage and the operating point of the newly added turbine stage. The preset percentage threshold is the percentage decrease in the total theoretical work in the recalculated result relative to the initial total theoretical work; Output the total number of turbine stages and the total set of turbine operating points, wherein the total set of turbine operating points includes all newly added turbine operating points and the operating point of the final turbine stage.

[0017] The configuration module in the apparatus provided in this disclosure embodiment is specifically used for: The heat exchangers in the cryogenic temperature zone turbine section are configured based on the total number of turbine stages and the total set of turbine operating points. Based on the turbine parameters corresponding to each turbine operating point in the total turbine operating point set, the minimum heat transfer temperature difference of each heat exchanger in the configuration result is calculated. The total turbine operating point set is verified according to the minimum heat transfer temperature difference. Based on the verification result, heat exchangers that do not meet the second preset condition are determined, and a list of heat exchangers to be adjusted is obtained. Calculate the temperature difference margin based on the minimum heat transfer temperature difference and the second preset condition, determine the correction target value of the list of heat exchangers to be adjusted based on the temperature difference margin, calculate the supplementary operating point based on the correction target value using the preset parameter configuration method, adjust the configuration of the heat exchangers in the cryogenic temperature zone turbine section based on the supplementary operating point, and add the supplementary operating point to the total turbine operating point set. Based on the turbine parameters corresponding to the supplemented total turbine operating point set, the minimum heat transfer temperature difference of each heat exchanger in the configuration adjustment result is calculated. If there are still heat exchangers that do not meet the second preset condition, a second supplement is performed until all heat exchangers meet the second preset condition. The corresponding total turbine operating point set is then output as the turbine operating point set to be used.

[0018] The output module of the apparatus provided in this disclosure embodiment is specifically used for: Extract the outlet pressure of the last stage turbine operating point in the set of turbine operating points to be used, compare the outlet pressure with the preset critical pressure, if the outlet pressure is less than or equal to the preset critical pressure, then there is no need to add a main turbine operating point. Then, organize the inlet and outlet temperatures, pressures, flow rates and all heat exchanger temperature nodes of each turbine operating point in the set of turbine operating points to be used to obtain the refrigeration process parameters. If the outlet pressure is greater than the preset critical pressure, it is determined that a new main road turbine operating point needs to be added. The outlet pressure corresponding to the main road turbine operating point is compared with the preset critical pressure. If the outlet pressure is greater than the preset critical pressure, it is determined that a new main road turbine operating point needs to be added. This process continues until the outlet pressure corresponding to the newly added main road turbine operating point is less than or equal to the preset critical pressure, at which point the addition of a new main road turbine operating point is stopped.

[0019] This disclosure also provides an electronic device, the electronic device comprising: a processor; a memory for storing executable instructions of the processor; the processor being configured to read the executable instructions from the memory and execute the instructions to implement the multi-stage turbine cooling cycle design method provided in this disclosure.

[0020] This disclosure also provides a computer-readable storage medium storing a computer program for executing the multi-stage turbine refrigeration cycle design method provided in this disclosure.

[0021] The technical solution provided in this disclosure has the following advantages compared with the prior art: This disclosure provides a multi-stage turbine refrigeration cycle design method. After determining the basic boundary conditions, the operating point of the final-stage turbine is obtained through iterative optimization. Based on the operating point of the final-stage turbine, the initial compressor flow rate and initial total theoretical work are calculated. New turbine operating points are determined by recursion towards increasing temperature. The power consumption reduction benefit is used to determine whether to continue adding stages. The total number of turbine stages and the total turbine operating point set are output by combining the new turbine operating points and the final-stage turbine operating point set. The heat exchangers in the cryogenic temperature zone turbine section are configured according to the total number of turbine stages and the total turbine operating point set, and the configuration results are verified. Based on the verification results and a second preset condition, the heat exchangers and the total turbine operating point set are iteratively adjusted to output a set of turbine operating points to be used. The main circuit turbine operating points are determined and supplemented through pressure comparison to obtain the overall turbine operating point set. Refrigeration process parameters are determined based on the overall turbine operating point set. Through iterative optimization of the final-stage turbine and recursion of each stage, the total power consumption of the system is minimized, reducing energy consumption. By verifying the temperature difference of the heat exchanger and adding a main turbine, the heat exchange robustness and throttling efficiency of the cryogenic section are improved, making the process parameters more reasonably matched. Attached Figure Description

[0022] The above and other features, advantages, and aspects of the embodiments of this disclosure will become more apparent from the accompanying drawings and the following detailed description. Throughout the drawings, the same or similar reference numerals denote the same or similar elements. It should be understood that the drawings are schematic, and the originals and elements are not necessarily drawn to scale.

[0023] Figure 1 A schematic flowchart illustrating a multi-stage turbine refrigeration cycle design method provided in this embodiment of the disclosure; Figure 2 This is a diagram showing the closed-loop verification and layout of the entire process of equipment node parameters provided in the embodiments of this disclosure; Figure 3 This is a flowchart of the iterative optimization method for the outlet temperature of the final stage turbine according to an embodiment of this disclosure; Figure 4 A flowchart for determining the inlet temperature of the final stage turbine in an embodiment of this disclosure; Figure 5 This is a schematic diagram of a multi-stage turbine refrigeration cycle design device provided in an embodiment of the present disclosure; Figure 6 This is a schematic diagram of the structure of an electronic device provided in an embodiment of the present disclosure. Detailed Implementation

[0024] Embodiments of this disclosure will now be described in more detail with reference to the accompanying drawings. While some embodiments of this disclosure are shown in the drawings, it should be understood that this disclosure can be implemented in various forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided to provide a more thorough and complete understanding of this disclosure. It should be understood that the accompanying drawings and embodiments of this disclosure are for illustrative purposes only and are not intended to limit the scope of protection of this disclosure.

[0025] It should be understood that the steps described in the method embodiments of this disclosure may be performed in different orders and / or in parallel. Furthermore, the method embodiments may include additional steps and / or omit the steps shown. The scope of this disclosure is not limited in this respect.

[0026] The term "comprising" and its variations as used herein are open-ended inclusions, meaning "including but not limited to". The term "based on" means "at least partially based on". The term "one embodiment" means "at least one embodiment"; the term "another embodiment" means "at least one additional embodiment"; the term "some embodiments" means "at least some embodiments". Definitions of other terms will be given in the description below.

[0027] It should be noted that the concepts of "first" and "second" mentioned in this disclosure are used only to distinguish different devices, modules or units, and are not used to limit the order of functions performed by these devices, modules or units or their interdependencies.

[0028] It should be noted that the terms "a" and "a plurality of" used in this disclosure are illustrative rather than restrictive, and those skilled in the art should understand that, unless otherwise expressly indicated in the context, they should be understood as "one or more".

[0029] The names of messages or information exchanged between multiple devices in the embodiments of this disclosure are for illustrative purposes only and are not intended to limit the scope of such messages or information.

[0030] To address the aforementioned problems, this disclosure provides a multi-stage turbine refrigeration cycle design method, which will be described below with reference to specific embodiments.

[0031] Figure 1 This is a flowchart illustrating a multi-stage turbine refrigeration cycle design method provided in an embodiment of the present disclosure. The method can be executed by a multi-stage turbine refrigeration cycle design device, which can be implemented in software and / or hardware and is generally integrated into an electronic device.

[0032] Example 1: This embodiment of the present disclosure provides a multi-stage turbine refrigeration cycle design method, such as... Figure 1 As shown, it includes: S101: Determine the basic boundary conditions based on user requirements and compressor parameters, and perform iterative optimization of the final stage turbine based on the basic boundary conditions and preset parameter configuration method to determine the operating point of the final stage turbine. The operating point of the final stage turbine includes the outlet temperature, the inlet temperature and the final stage turbine setting framework. S102: Calculate the initial compressor flow rate and initial total theoretical work of each stage based on the operating point of the last stage turbine, and proceed step by step in the direction of increasing temperature to determine the new turbine operating point. If the power consumption reduction benefit corresponding to the new turbine operating point meets the first preset condition, output the total number of turbine stages and the total set of turbine operating points. S103: Configure the heat exchanger of the cryogenic temperature zone turbine section based on the total number of turbine stages and the total turbine operating point set; verify the total turbine operating point set according to the configuration result; if the verification result meets the second preset condition, output the turbine operating point set to be used. S104: Compare the outlet pressure of the last stage turbine operating point in the set of turbine operating points to be used with the preset critical pressure, determine the main turbine operating point based on the comparison result, and add the main turbine operating point to the set of turbine operating points to be used to obtain the overall turbine operating point set, and determine and output the refrigeration process parameters based on the overall turbine operating point set.

[0033] In this embodiment, user requirements are the design goals, including refrigeration temperature, refrigeration capacity, or liquefaction rate, which determine the thermodynamic performance indicators that the system must achieve. Compressor parameters are hardware constraints, including rated pressure ratio, efficiency, and allowable pressure range, limiting the achievable range of high and low pressure in the system. User requirements and compressor parameters together determine the basic boundary conditions, which form the input framework for subsequent calculations, including the system high pressure, low pressure, pre-cooling temperature, and target refrigeration capacity. The preset parameter configuration method is a predefined set of calculation rules, including a preset first parameter configuration method (i.e., the final stage turbine outlet temperature determination sub-method) and a preset second parameter configuration method (i.e., the helium turbine expander setting and parameter determination sub-method), used to derive unknown parameters from known boundaries in each step. The basic boundary conditions and preset parameter configuration methods drive the iterative optimization process. The iterative optimization process assumes multiple final stage outlet temperatures and calculates the corresponding total compressor flow rate, finding the temperature point that minimizes the total flow rate through minimum value optimization, thereby determining the operating point of the final stage turbine. The operating point of the final-stage turbine is the set of thermodynamic states of the final-stage turbine, including the outlet temperature, inlet temperature, and outlet temperature. The outlet temperature is determined by iterative optimization, while the inlet temperature is determined by back calculation and multivariate correction. The operating point of the final-stage turbine is the starting point for reverse recursion. After the operating point of the final-stage turbine is determined, the initial compressor flow rate and initial total theoretical work of each stage are calculated based on the operating point of the final-stage turbine. The initial compressor flow rate of each stage is obtained by power balance iteration from the Joule-Thomson throttling path flow rate (JT throttling path flow rate) and the turbine path flow rate. The initial total theoretical work is the sum of the compression power consumption corresponding to the initial compressor flow rate of each stage, which serves as the benchmark for subsequent power consumption and benefit comparison. After the initial total theoretical work is determined, the recursion proceeds in the direction of increasing temperature. The inlet temperature of the final-stage turbine is used as the outlet temperature of the new stage. The preset parameter configuration method is called to determine the operating point of the new turbine. The new turbine operating point includes the inlet and outlet temperatures and the setting structure of the new stage, representing the thermodynamic state after adding one stage of turbine. The total theoretical work is recalculated jointly by the newly added turbine operating point and the final turbine operating point. This recalculated work is compared with the initial total theoretical work to obtain the power consumption reduction benefit. The power consumption reduction benefit is the relative percentage decrease in total power consumption after adding the turbine, reflecting the economic value of the upgrade. The power consumption reduction benefit is compared with a first preset condition, which includes a preset percentage threshold and a preset liquid nitrogen temperature. The percentage threshold is the minimum passing standard for the upgrade benefit, and the liquid nitrogen temperature is the upper limit of the upgrade temperature constraint. When the power consumption reduction benefit meets the first preset condition, the upgrade stops, and the total number of turbine stages and the total set of turbine operating points are output. The total number of turbine stages is the final determined number of turbines connected in series, and the total set of turbine operating points includes the complete thermodynamic state parameters of the final stage and all newly added turbines. The total number of turbine stages and the total set of turbine operating points drive the configuration process of the heat exchangers in the cryogenic turbine section. The configuration process involves dividing the cryogenic section heat exchangers into multiple stages and arranging them between the operating points of each turbine stage, forming an initial network of alternating series connections between turbines and heat exchangers. After configuration, the configuration results are obtained, which include the initial heat load, end temperature difference, and node temperature distribution of each heat exchanger.The process of verifying the configuration results involves calculating the minimum heat transfer temperature difference for each heat exchanger based on turbine parameters and determining whether it meets a second preset condition. The second preset condition is that the minimum heat transfer temperature difference of all heat exchangers must be greater than or equal to a preset safety threshold. If any heat exchanger does not meet the second preset condition, the temperature difference margin is calculated, the turbine operating point is fine-tuned, and the result is added to the total turbine operating point set before re-verification. This process continues until the verification results meet the second preset condition, at which point a set of turbine operating points to be used is output. This set of turbine operating points to be used is the final turbine parameter set after temperature difference robustness verification. The outlet pressure of the last-stage turbine operating point in the set of turbine operating points to be used is compared with the preset critical pressure, which is the critical pressure of helium, and serves as a criterion for whether a main turbine needs to be added. If the outlet pressure is greater than the preset critical pressure, a main turbine operating point is added. The main turbine operating point is the thermodynamic state of an additional turbine connected in series after the last-stage turbine, used to expand the supercritical pressure to below the critical pressure. After the main turbine operating points are supplemented into the set of turbine operating points to be used, a complete turbine operating point set is formed. The complete turbine operating point set is a complete set of parameters containing all turbines. Based on the complete turbine operating point set, the refrigeration process parameters are organized and output. The refrigeration process parameters are the final delivered system design results, including the inlet and outlet temperatures, pressures, and flow rates of each turbine stage, heat exchanger node temperatures, and parameters before and after the JT valve.

[0034] Specifically, Figure 1 S101 in the middle corresponds to Figure 2 The starting point of the final stage turbine is determined by setting the basic boundary based on user requirements and compressor parameters. The operating point of the final stage turbine (including outlet temperature, inlet temperature and setting structure) is determined through iterative optimization and serves as the design anchor point for the entire process. Figure 1 S102 in the middle corresponds to Figure 2 The system determines the inlet and outlet temperatures, sets the turbine cycle, calculates the initial compressor flow rate and total theoretical power based on the final stage operating point, and enters a step-by-step reverse recursive cycle. The inlet temperature of the previous stage is used as the outlet temperature of the current stage, and the turbine setting method is called to determine the operating point of the new stage. The power consumption reduction of 10%~20% is used as the criterion for continuing to add stages, and the inlet temperature ≤80K (preset liquid nitrogen temperature) is used as the stop boundary. The system outputs the total number of turbine stages and the total set of turbine operating points. Figure 1 S103 in the middle corresponds to Figure 2 The system determines the temperature and heat exchanger, as well as the heat exchanger layout / inlet / outlet temperature path. Based on the determined total number of turbine stages and operating point set, it configures the heat exchangers in the cryogenic temperature zone turbine section (which can be arranged in segments between each turbine stage). It also verifies the consistency between the inlet / outlet temperatures of each turbine stage and the node temperatures of the heat exchangers through heat balance. Once the preset conditions are met, it outputs the operating point set of the turbines to be used. Figure 1 S104 in the middle corresponds to Figure 2The main circuit turbine, JT throttling valve, and refrigeration capacity outlet are compared with the final stage outlet pressure of the working point set. If the pressure is greater than the critical value, the main circuit turbine is added stage by stage (requiring the outlet to be supercritical) until the outlet pressure is less than or equal to the preset critical pressure. The main circuit turbine working point is then added to the working point set. At the same time, the inlet and outlet state parameters of the high-pressure / medium-pressure / low-pressure JT throttling valve are determined. Combined with the refrigeration capacity requirements, the inlet and outlet temperatures of the heat exchanger are finally determined and indirectly verified, and the complete refrigeration process parameters are output.

[0035] The working principle and beneficial effects of this embodiment are as follows: After determining the basic boundary conditions, the operating point of the final-stage turbine is obtained through iterative optimization. Based on the operating point of the final-stage turbine, the initial compressor flow rate and initial total theoretical work are calculated. New turbine operating points are determined by progressive recursion in the direction of increasing temperature. The benefit of reduced power consumption is used to determine whether to continue adding stages. The total number of turbine stages and the total turbine operating point set are output by combining the new turbine operating points and the final-stage turbine operating points. The heat exchangers in the cryogenic temperature zone turbine section are configured according to the total number of turbine stages and the total turbine operating point set, and the configuration results are verified. Based on the verification results and a second preset condition, the heat exchangers and the total turbine operating point set are iteratively adjusted, and a set of turbine operating points to be used is output. The main circuit turbine operating points are determined and supplemented through pressure comparison to obtain the overall turbine operating point set. The refrigeration process parameters are determined based on the overall turbine operating point set. Through iterative optimization of the final-stage turbine and progressive recursion, the total power consumption of the system is minimized, reducing energy consumption. By verifying the temperature difference of the heat exchanger and adding a main turbine, the heat transfer robustness and throttling efficiency of the cryogenic section are improved, resulting in a more reasonable matching of process parameters. By optimizing the outlet temperature of the final-stage precooling turbine, the work done by Brayton expansion and the throttling liquefaction of the JT are balanced.

[0036] Example 2: The method provided in this embodiment determines basic boundary conditions based on user requirements and compressor parameters, and iteratively optimizes the final stage turbine based on the basic boundary conditions and a preset parameter configuration method to determine the operating point of the final stage turbine, such as... Figure 3 As shown, it includes: The first iteration condition is determined based on the aforementioned basic boundary conditions; Based on the first iteration condition and the preset first parameter configuration method, several initial temperatures are assumed and iterated. Based on the preset accuracy condition, the outlet temperature of the final turbine is determined from the iteration results of all initial temperatures. The inlet and outlet pressures of the final stage turbine are determined based on the basic boundary conditions. The final stage turbine configuration framework and the inlet temperature of the final stage turbine are determined by back calculation based on the inlet and outlet pressures of the final stage turbine, the outlet temperature of the final stage turbine and the helium adiabatic index, using the preset second parameter configuration method. The operating point of the final stage turbine is determined by combining the outlet temperature, the final stage turbine configuration, and the inlet temperature.

[0037] In this embodiment, the first iteration condition is the iterative search range and step size derived from the basic boundary conditions, including the global search upper and lower limits and coarse sweep step size for the final stage outlet temperature. After the first iteration condition is determined, a preset first parameter configuration method is driven. This preset first parameter configuration method is a calculation rule for the coupling optimization of the Joule-Thomson throttling path (JT throttling path) and turbine flow rate, used to obtain the total system flow rate from the assumed temperature. The preset first parameter configuration method requires an initial temperature as input. The initial temperature is multiple candidate outlet temperature values ​​assumed within the search range according to the first iteration condition and with a coarse step size, serving as a trial point for iterative optimization. Each initial temperature is used to calculate the corresponding total compressor flow rate. After plotting the relationship curve between all initial temperatures and total flow rates, a minimum value optimization is performed. The optimization result needs to be judged by a preset accuracy condition, which is the tolerance criterion for iterative convergence, requiring that the temperature change between two adjacent calculations near the optimal temperature point be less than or equal to a preset value. When the preset accuracy condition is met, the final stage turbine outlet temperature is output. After the final stage turbine outlet temperature is determined, the basic boundary conditions determine the inlet and outlet pressures of the final stage turbine. The outlet temperature, inlet and outlet pressures, and helium adiabatic index are collectively input into a preset second parameter configuration method. The helium adiabatic index is a constant for the isentropic expansion process of helium. The preset second parameter configuration method includes a set of calculation rules encompassing isentropic relationship calculations and engineering feasibility verification. The core operation of the preset second parameter configuration method is inverse calculation, which is a thermodynamic calculation process that reverses the process of solving for the ideal inlet temperature based on the outlet state and pressure ratio. The inverse calculation result is obtained by estimating the polytropic index and obtaining the inlet temperature. Simultaneously, after verification within the engineering feasibility range, the final stage turbine configuration framework is determined. The final stage turbine configuration framework is the internal stage scheme of the final stage turbine, including the number of turbine stages and the ideal specific enthalpy drop per stage. The set of outlet temperature, final stage turbine configuration framework, and inlet temperature constitutes the operating point of the final stage turbine.

[0038] Specifically, by working backward from the final stage temperature and pressure parameters, the temperature and pressure of each stage are precisely matched according to the Carnot step size allocation principle, gradually approaching the Carnot efficiency. Guided by the optimal comprehensive benefits of system power consumption and equipment cost, the outlet temperature of the final stage precooled turbine is optimized to balance the work done by Brayton expansion and JT throttling liquefaction. At the same time, by judging the power consumption reduction benefits brought by increasing the number of turbine stages, a reasonable trade-off is made between "increasing the number of turbine stages" and "controlling equipment cost and complexity", avoiding simply pursuing the minimization of power consumption while ignoring engineering feasibility.

[0039] The working principle and beneficial effects of this embodiment are as follows: First iteration conditions are determined through basic boundary conditions. An initial temperature is assumed based on the first iteration conditions and a preset first parameter configuration method, and iteration is performed. The outlet temperature of the final-stage turbine is determined based on preset accuracy conditions. The inlet and outlet pressures of the final-stage turbine are determined based on the basic boundary conditions. The final-stage turbine setup and inlet temperature are determined by back-calculation based on the inlet and outlet pressures, outlet temperature, and helium adiabatic index using a preset second parameter configuration method. The operating point of the final-stage turbine is determined by combining the outlet temperature, setup, and inlet temperature. The outlet temperature is determined through iterative optimization to minimize the total system flow. The setup and inlet temperature are determined through back-calculation to ensure that the single-stage enthalpy drop and velocity are within the engineering feasible range, resulting in more reasonable parameter matching for the final-stage turbine and providing a reliable starting point for subsequent stage recursion.

[0040] Example 3: The method provided in this embodiment of the present disclosure assumes several initial temperatures based on the first iteration condition and a preset first parameter configuration method, and iterates through them. Based on a preset accuracy condition, the exit temperature of the final stage turbine is determined from the iteration results of all initial temperatures, including: Based on the first iteration condition and the preset first parameter configuration method, several initial temperatures are assumed. Based on the first iteration condition and the preset Joule-Thomson throttling process, the temperature calculation point corresponding to each initial temperature is determined, and the required mass flow rate of the Joule-Thomson throttling path at the corresponding temperature calculation point is obtained. The total compressor flow rate at the corresponding initial temperature is obtained by summing the mass flow rates at all temperature calculation points corresponding to each initial temperature. Based on all initial temperatures and the corresponding total flow rate of the compressor, a relationship curve is plotted. Based on preset screening conditions, the minimum value is optimized in the relationship curve to determine the candidate outlet temperature. The accuracy of the candidate outlet temperature is determined according to the preset accuracy condition. If the accuracy of the candidate outlet temperature meets the preset accuracy condition, the candidate outlet temperature is output as the outlet temperature of the final stage turbine. If the accuracy of the candidate outlet temperature does not meet the preset accuracy condition, then a second iteration condition is determined based on the basic boundary condition, and a new initial temperature is assumed based on the second iteration condition and the candidate outlet temperature to obtain a new candidate outlet temperature, until a candidate outlet temperature meets the preset accuracy condition, and the candidate outlet temperature is output as the outlet temperature of the final stage turbine.

[0041] In this embodiment, after assuming an initial temperature based on the first iteration condition and the preset first parameter configuration method, each initial temperature needs to be substituted into a preset Joule-Thomson throttling process for calculation. The preset Joule-Thomson throttling process is the thermodynamic calculation rule of the JT throttling cycle. Based on the high pressure and the initial temperature, the enthalpy and dryness fraction of the working fluid after throttling are calculated, thereby determining the unit cooling capacity. The preset Joule-Thomson throttling process outputs temperature calculation points, which are temperature nodes of each section in the heat exchanger network, obtained through iterative calculation of the heat exchange energy balance of multiple streams. Each temperature calculation point corresponds to the required mass flow rate of a Joule-Thomson throttling path, which is the local mass flow rate at each temperature calculation point determined by the ratio of cooling capacity demand to unit cooling capacity. The required mass flow rates of the Joule-Thomson throttling path at all temperature calculation points at each initial temperature are summed and combined with the turbine flow rate to obtain the total compressor flow rate corresponding to the initial temperature. All initial temperatures and their corresponding total compressor flow rates constitute a discrete data set. A relationship curve is then plotted based on this data. This curve is a two-dimensional curve with the initial temperature on the x-axis and the total compressor flow rate on the y-axis, reflecting the variation of the total flow rate with the outlet temperature. After plotting the relationship curve, a minimum value search is performed based on preset screening criteria. These criteria determine the optimal solution, and the minimum value search involves searching for the temperature value corresponding to the lowest point of the total compressor flow rate on the relationship curve. The minimum value search result is output as a candidate outlet temperature, which is the optimal temperature estimate whose accuracy needs to be verified. The candidate outlet temperature must be judged by preset accuracy conditions. If the preset accuracy conditions are not met, the basic boundary conditions determine the second iteration conditions. The second iteration conditions are a narrowed search range and a finer step size centered on the candidate outlet temperature, used for fine iteration near the optimal temperature until the candidate outlet temperature meets the preset accuracy conditions. The output is the final stage turbine outlet temperature.

[0042] Specifically, such as Figure 3 As shown, in the coarse scan stage: discrete temperature points (e.g., 6, 7, 8…20K) are selected in a step size of 1K within the range of 6~20K. For each assumed outlet temperature, the flow rate of the JT throttling path and the turbine expansion work are calculated in combination with the high pressure and JT throttling cycle optimization, and then the corresponding total compressor flow rate is obtained. The relationship curve of "outlet temperature - total compressor flow rate" is plotted. Since the outlet temperature of the last stage turbine has opposite effects on the flow rates of the JT path and the turbine path, the curve has a minimum point. The temperature corresponding to this point is the candidate optimal outlet temperature. In the fine scan stage: it is determined whether the accuracy of the candidate temperature meets the requirement of error ≤0.1K. If it does not meet the requirement, the step size is reduced in the neighborhood of the candidate point (e.g., 0.05K) and recalculated. The optimization is repeated until the error meets the standard, and finally the optimal outlet temperature of the last stage turbine is determined.

[0043] The working principle and beneficial effects of this embodiment are as follows: An initial temperature is assumed using a first iteration condition and a preset first parameter configuration method. The temperature calculation point is determined based on a preset Joule-Thomson throttling process, and the mass flow rate of the Joule-Thomson throttling path is obtained. The total compressor flow rate is obtained by summing all mass flow rates. A relationship curve is plotted, and the candidate outlet temperature is determined by minimizing the relationship curve. Accuracy is judged according to preset accuracy conditions. If the conditions are met, the final turbine outlet temperature is output; otherwise, a second iteration condition is determined, and a new initial temperature is assumed until the candidate outlet temperature meets the preset accuracy conditions. Through the coupled iteration of the Joule-Thomson throttling path and the total compressor flow rate, the outlet temperature is determined by minimizing the temperature, reducing energy consumption. The iteration convergence is controlled by preset accuracy conditions, ensuring accurate and reliable outlet temperature.

[0044] Example 4: The method provided in this embodiment of the present disclosure determines the inlet and outlet pressures of the final stage turbine based on the basic boundary conditions, and determines the final stage turbine setup structure and the inlet temperature of the final stage turbine based on the preset second parameter configuration method using the inlet and outlet pressures of the final stage turbine, the outlet temperature of the final stage turbine, and the helium adiabatic index. This includes: The ideal inlet temperature of the turbine is calculated based on the inlet and outlet pressures of the final stage turbine, the outlet temperature of the final stage turbine, and the helium adiabatic index. The ideal inlet specific enthalpy is obtained by referring to the preset property table based on the ideal inlet temperature of the turbine and the inlet pressure of the final stage turbine. The inlet and outlet specific enthalpy of the turbine is obtained by referring to the preset property table based on the inlet and outlet pressures and outlet temperature of the final turbine. The ideal specific enthalpy drop is obtained by subtracting the ideal specific enthalpy from the turbine inlet and outlet specific enthalpy. The maximum ideal speed of the expander is then calculated based on the ideal specific enthalpy drop. If either the maximum ideal speed of the expander or the ideal specific enthalpy drop exceeds the preset engineering feasible range for a single-stage turbine, the final-stage turbine is split. Based on the splitting result, the ideal turbine inlet temperature, the maximum ideal speed of the expander, and the ideal specific enthalpy drop are recalculated until both the maximum ideal speed of the expander and the ideal specific enthalpy drop are within the preset engineering feasible range for a single-stage turbine. If so, the splitting result is deemed valid, and a final-stage turbine configuration framework including the number of turbine stages and the ideal specific enthalpy drop is determined based on the splitting result. The polytropic index is determined based on the initial number of turbine stages in the final turbine configuration, and the ideal inlet temperature of the final turbine is calculated based on the polytropic index.

[0045] In this embodiment, the inlet and outlet pressures and outlet temperature of the final-stage turbine are input into the isentropic relationship with the helium adiabatic index to calculate the ideal inlet temperature of the turbine. The ideal inlet temperature is the theoretical temperature that the inlet should reach under the assumption of isentropic expansion, and it depends only on the outlet state and pressure ratio. The ideal inlet temperature and the inlet pressure of the final-stage turbine are consulted together in a preset property table, which is a database of helium thermodynamic properties. Inputting pressure and temperature returns the corresponding specific enthalpy value. The result yields the ideal inlet specific enthalpy, which corresponds to the hypothetical inlet state of the ideal process and serves as the work benchmark. Simultaneously, the inlet and outlet specific enthalpies of the turbine are obtained by consulting the preset property table based on the inlet and outlet pressures and outlet temperature of the final-stage turbine. These inlet and outlet specific enthalpies correspond to the specific enthalpies of the turbine's actual outlet state. The difference between the ideal inlet specific enthalpy and the inlet and outlet specific enthalpies yields the ideal specific enthalpy drop, which is the maximum energy released per unit mass of working fluid during ideal expansion. The ideal enthalpy drop is used to calculate the maximum ideal speed of the expander. The maximum ideal speed of the expander is the absolute velocity at the outlet of the ideal expansion process, obtained from the ideal enthalpy drop through the energy equation, reflecting the work intensity of a single-stage turbine. The maximum ideal speed and ideal enthalpy drop of the expander are compared with the preset engineering feasible range of a single-stage turbine. The preset engineering feasible range of a single-stage turbine is an upper limit for enthalpy drop and a speed limit set according to processing capacity and aerodynamic performance. If either exceeds the limit, splitting is triggered. Splitting is the operation of dividing a turbine into multiple turbines in series. After splitting, the enthalpy drop and speed of each stage are reduced. The splitting results are used to recalculate the ideal inlet temperature of the turbine, the maximum ideal speed of the expander, and the ideal enthalpy drop, and are verified again until they are all within the engineering feasible range. The output is the final stage turbine configuration framework including the number of turbine stages and the ideal enthalpy drop. The initial turbine stage number in the final stage turbine configuration determines the polytropic index, which is an index describing the loss characteristics of the actual expansion process. It is obtained by selecting an empirical polytropic efficiency corresponding to the stage number and then converting it using a formula. The polytropic index is used to correct the ideal turbine inlet temperature to obtain the final stage turbine inlet temperature.

[0046] Specifically, in the pre-cooling temperature zone, turbines are added as much as possible to split the enthalpy drop. The enthalpy drop is split according to the Carnot step size to reduce the single-stage temperature drop, which significantly reduces irreversible losses. The actual polytropic index is introduced to correct the irreversible losses in the expansion process, so that the theoretically calculated temperature and enthalpy drop parameters are closer to the actual operating conditions, improving the engineering usability of the design results. At the same time, by checking the single-stage enthalpy drop and setting intermediate pressure nodes, the total expansion ratio is reasonably allocated to reduce the single-stage enthalpy drop while ensuring efficiency, thereby improving the manufacturability and operational stability of turbine components.

[0047] Specifically, such as Figure 4 As shown, the ideal calculation stage involves calculating the ideal inlet temperature and ideal specific enthalpy drop based on the turbine inlet and outlet pressures and outlet temperature, and the working fluid adiabatic index k (k=1.67 for helium), thereby obtaining the ideal maximum expansion rate. The corresponding specific formula is... ,in, This indicates the turbine outlet temperature; k represents the adiabatic index. Indicates the ideal inlet temperature; This indicates pressure on turbine exports; This indicates pressure on turbine imports; ,in, This indicates the maximum ideal speed of the expander; This indicates the ideal specific enthalpy drop; ,in, Indicates turbine inlet temperature; n represents the pluralistic index; and so on. Feasibility criteria for single-stage turbines: ≤500 is easy to design. A range of 500 to 550 is acceptable. If the value is greater than 550, it needs to be split. Splitting and correction phase: If... or If the project exceeds the feasible scope of a single-stage project, the turbine will be split into two options: Option 1 maintains consistent high and low pressure ratios and pressure ratios across all stages (preferred, fewer turbines are better); Option 2 adjusts the outlet pressure to medium pressure; if neither option satisfies the requirements, a combination of Option 1 and Option 2 will be used. The calculations will be re-evaluated after the split. and The process continues until all parameters are within a feasible range, at which point the process architecture (including the number of stages and enthalpy drop distribution) is determined. Finally, based on this architecture, a practical polytropic index n (typically 1.35~1.45) is selected, and the ideal inlet temperature is corrected for non-ideal conditions to obtain the final turbine inlet temperature. Essentially, this method is a design approach that uses maximum velocity and enthalpy drop as constraints, and ensures the feasibility of a single-stage turbine through iterative decomposition.

[0048] The working principle and beneficial effects of this embodiment are as follows: The ideal inlet temperature of the turbine is calculated by using the inlet and outlet pressures, outlet temperature, and helium adiabatic index. The ideal specific enthalpy at the inlet and the inlet and outlet specific enthalpy of the turbine are obtained by consulting a preset property table, and the difference is used to obtain the ideal specific enthalpy drop. The maximum ideal speed of the expander is calculated. If the maximum ideal speed or ideal specific enthalpy drop of the expander exceeds the engineering feasible range, the final stage turbine is split, and the calculation is repeated until both are within the engineering feasible range. The splitting result is then determined, and the final stage turbine setup framework, including the number of turbine stages and the ideal specific enthalpy drop, is determined. The polytropic index is determined based on the initial number of turbine stages, and the ideal inlet temperature of the turbine is corrected based on the polytropic index to obtain the inlet temperature. Through engineering feasible range verification and turbine splitting, it is ensured that the single-stage enthalpy drop and speed do not exceed the limits, improving the engineering feasibility of the final stage turbine. By correcting the inlet temperature with the polytropic index, the inlet temperature is made more consistent with the actual expansion process, and the accuracy of the parameters is improved.

[0049] Example 5: The method provided in this embodiment calculates the initial compressor flow rate and initial total theoretical work of each stage based on the operating point of the final turbine stage, and proceeds step-by-step in the direction of increasing temperature to determine the new turbine operating point. If the power consumption reduction benefit corresponding to the new turbine operating point meets a first preset condition, the total number of turbine stages and the total set of turbine operating points are output, including: Calculate the initial compressor flow rate of each stage based on the operating point of the final turbine, and sum the initial total theoretical work by summing the flow rates of all initial compressors. The inlet temperature of the last stage turbine operating point is used as the outlet temperature of the new turbine. The inlet temperature of the new turbine and the new turbine setting structure are determined according to the preset second parameter configuration method in the preset parameter configuration method. The operating point of the new turbine is determined based on the outlet temperature of the new turbine, the inlet temperature of the new turbine, and the new turbine configuration. Based on the newly added turbine operating point and the final stage turbine operating point, the flow rate and total theoretical work of each stage compressor are recalculated to obtain the recalculation results. Based on the recalculation results, the power consumption reduction benefit obtained due to the newly added turbine operating point is determined, and the power consumption reduction benefit is compared with the first preset condition. The first preset condition includes a preset percentage threshold and a preset liquid nitrogen temperature; If the power consumption reduction benefit is higher than the preset percentage threshold, the inlet temperature of the new turbine operating point is compared with the preset liquid nitrogen temperature. If the inlet temperature of the new turbine operating point is higher than the preset liquid nitrogen temperature, the stage addition is stopped, and the total number of turbine stages is determined based on the last turbine operating point and the new turbine operating point. If the inlet temperature of the new turbine operating point is lower than the preset liquid nitrogen temperature, the inlet temperature of the new turbine operating point is used as the outlet temperature for continuing to add turbines, and the process is repeated to obtain the new turbine operating points. The power consumption reduction benefit is then recalculated and compared. If the power consumption reduction benefit is lower than the preset percentage threshold, the total number of turbine stages is determined based on the operating point of the final turbine stage and the operating point of the newly added turbine stage. The preset percentage threshold is the percentage decrease in the total theoretical work in the recalculated result relative to the initial total theoretical work; Output the total number of turbine stages and the total set of turbine operating points, wherein the total set of turbine operating points includes all newly added turbine operating points and the operating point of the final turbine stage.

[0050] In this embodiment, after the operating point of the final stage turbine is determined, the outlet temperature of the newly added turbine is directly taken from the inlet temperature of the final stage turbine's operating point. The outlet temperature of the newly added turbine is the outlet state of the second-to-last stage turbine in the first step of the reverse recursion, inherited from the inlet of the pre-designed next-stage turbine. The outlet temperature of the newly added turbine is input into a preset parameter configuration method to calculate the inlet temperature of the newly added turbine. The inlet temperature of the newly added turbine is the inlet state of the newly added turbine after back calculation and multivariate correction. At the same time, the preset parameter configuration method outputs the setting framework of the newly added turbine. The setting framework of the newly added turbine is the internal stage scheme of the newly added turbine after verification of engineering feasibility. The outlet temperature, inlet temperature, and setting framework of the newly added turbine together constitute the operating point of the newly added turbine. The total theoretical work is recalculated jointly by the operating point of the newly added turbine and the operating point of the final stage turbine, and compared with the initial total theoretical work to obtain the power consumption reduction benefit. The power consumption reduction benefit is compared with a preset percentage threshold, which is the minimum power consumption reduction ratio to determine whether the upgrade is economically worthwhile. When the power consumption reduction benefit exceeds a preset percentage threshold, the comparison continues with a preset liquid nitrogen temperature. The preset liquid nitrogen temperature is the boiling point of the precooling medium liquid nitrogen, serving as an upper limit constraint on the turbine inlet temperature. When the newly added turbine inlet temperature is lower than the preset liquid nitrogen temperature, a recursive loop is triggered. The recursive loop uses the current newly added turbine inlet temperature as the outlet temperature for adding more turbines, repeating the iterative process of upgrading and power consumption determination. The recursive loop outputs the operating point for the next newly added turbine, which is the thermodynamic state parameter of the previous turbine stage. After the loop terminates, the total number of turbine stages and the total set of turbine operating points are output.

[0051] The working principle and beneficial effects of this embodiment are as follows: The initial compressor flow rate of each stage is calculated based on the operating point of the final-stage turbine, and the initial total theoretical work is obtained by summing the flow rates. The inlet temperature of the final-stage turbine is used as the outlet temperature of the new turbine. The inlet temperature and configuration structure of the new turbine are determined through a preset parameter configuration method, thereby determining the operating point of the new turbine. The total theoretical work is recalculated based on the operating point of the new turbine and the operating point of the final-stage turbine, resulting in a power consumption reduction benefit. The power consumption reduction benefit is compared with a preset percentage threshold. If the value is higher than the threshold, the inlet temperature is compared with a preset liquid nitrogen temperature. If the inlet temperature is higher than the liquid nitrogen temperature, the stage increase stops; if it is lower, the recursive loop continues. If the power consumption reduction benefit is lower than the threshold, the stage increase stops, and the total number of turbine stages and the total set of turbine operating points are output. By recursively determining the addition of new turbines and the power consumption reduction benefit, the optimal total number of turbine stages is automatically determined, avoiding excessive stage increase and minimizing the total power consumption of the system. Liquid nitrogen temperature boundary constraints ensure that the turbine inlet temperature does not exceed the limit, and the process parameters are reasonably matched.

[0052] Example 6: The method provided in this embodiment configures the heat exchanger in the cryogenic temperature zone turbine section based on the total number of turbine stages and the total turbine operating point set, verifies the total turbine operating point set according to the configuration result, and outputs the turbine operating point set to be used if the verification result meets the second preset condition, including: The heat exchangers in the cryogenic temperature zone turbine section are configured based on the total number of turbine stages and the total set of turbine operating points. Based on the turbine parameters corresponding to each turbine operating point in the total turbine operating point set, the minimum heat transfer temperature difference of each heat exchanger in the configuration result is calculated. The total turbine operating point set is verified according to the minimum heat transfer temperature difference. Based on the verification result, heat exchangers that do not meet the second preset condition are determined, and a list of heat exchangers to be adjusted is obtained. Calculate the temperature difference margin based on the minimum heat transfer temperature difference and the second preset condition, determine the correction target value of the list of heat exchangers to be adjusted based on the temperature difference margin, calculate the supplementary operating point based on the correction target value using the preset parameter configuration method, adjust the configuration of the heat exchangers in the cryogenic temperature zone turbine section based on the supplementary operating point, and add the supplementary operating point to the total turbine operating point set. Based on the turbine parameters corresponding to the supplemented total turbine operating point set, the minimum heat transfer temperature difference of each heat exchanger in the configuration adjustment result is calculated. If there are still heat exchangers that do not meet the second preset condition, a second supplement is performed until all heat exchangers meet the second preset condition. The corresponding total turbine operating point set is then output as the turbine operating point set to be used.

[0053] In this embodiment, after configuring the cryogenic temperature zone heat exchanger with the total number of turbine stages and the total turbine operating point set, turbine parameters are called for calculation. These turbine parameters are the inlet and outlet temperatures, pressures, and flow rates of each turbine operating point in the total turbine operating point set, serving as the boundary conditions for calculating the heat exchanger's heat load. The turbine parameters are input into the heat exchanger's heat balance equation to calculate the minimum heat transfer temperature difference. This minimum heat transfer temperature difference is the minimum temperature difference between the hot and cold fluids inside the heat exchanger, occurring at the pinch point. The minimum heat transfer temperature difference is compared with a second preset condition. Heat exchangers that do not meet the condition are included in the list of heat exchangers to be adjusted. This list consists of the heat exchanger numbers and their pinch point parameter sets indicating the objects requiring correction. The minimum heat transfer temperature difference is subtracted from the safety threshold of the second preset condition to calculate the temperature difference margin. This margin is the difference between the actual minimum temperature difference and the safety threshold, quantifying the size of the margin gap. The temperature difference margin drives the determination of the correction target value, which is the amount of temperature difference that needs to be increased to eliminate the margin gap. The target value is corrected by inputting preset parameter configuration methods to calculate supplementary operating points. These supplementary operating points are corrections to the upstream turbine outlet temperature and flow rate of the heat exchanger to be adjusted, used to change the fluid state entering the heat exchanger. After the supplementary operating points are added to the total turbine operating point set, configuration adjustments and re-verification are performed. If any heat exchangers still do not meet the conditions, a second supplement is triggered. This second supplement is an iterative operation of recalculating the corrected target value and supplementary operating points for heat exchangers that still do not meet the requirements, until all heat exchangers meet the second preset condition. Finally, a set of turbine operating points to be used is output.

[0054] The working principle and beneficial effects of this embodiment are as follows: The cryogenic heat exchanger is configured using the total number of turbine stages and the total set of turbine operating points. The minimum heat transfer temperature difference of the heat exchanger is calculated based on the turbine parameters corresponding to the total number of turbine stages and the total set of turbine operating points. The total set of turbine operating points is verified, a list of heat exchangers to be adjusted is determined, and the temperature margin is calculated based on the minimum heat transfer temperature difference and a second preset condition. The correction target value is determined, and supplementary operating points are calculated using a preset parameter configuration method. The configuration of the heat exchangers is adjusted, and the supplementary operating points are added to the total set of turbine operating points. The minimum heat transfer temperature difference is recalculated based on the supplemented turbine parameters. If any heat exchanger does not meet the second preset condition, a second supplement is performed until all heat exchangers meet the second preset condition. Finally, a set of turbine operating points to be used is output. By verifying the minimum heat transfer temperature difference and correcting the temperature margin, the cryogenic heat exchanger can maintain a safe heat transfer temperature difference under fluctuating operating conditions, improving system robustness. Iteratively supplementing operating points makes the matching between turbine parameters and heat exchangers more reasonable. By arranging heat exchangers in stages and controlling the temperature difference between each stage within a reasonable range, especially by strengthening the thermal matching between the precooling section and each stage turbine, the stability and adaptability of the system under different loads and operating conditions are improved, and the sensitivity to fluctuations in the parameters of a single component is reduced.

[0055] Example 7: The method provided in this embodiment compares the outlet pressure of the last-stage turbine operating point in the set of turbine operating points to be used with a preset critical pressure, determines the main turbine operating point based on the comparison result, and adds the main turbine operating point to the set of turbine operating points to be used, thus obtaining a complete turbine operating point set. Based on the complete turbine operating point set, refrigeration process parameters are determined and output, including: Extract the outlet pressure of the last stage turbine operating point in the set of turbine operating points to be used, compare the outlet pressure with the preset critical pressure, if the outlet pressure is less than or equal to the preset critical pressure, then there is no need to add a main turbine operating point. Then, organize the inlet and outlet temperatures, pressures, flow rates and all heat exchanger temperature nodes of each turbine operating point in the set of turbine operating points to be used to obtain the refrigeration process parameters. If the outlet pressure is greater than the preset critical pressure, it is determined that a new main road turbine operating point needs to be added. The outlet pressure corresponding to the main road turbine operating point is compared with the preset critical pressure. If the outlet pressure is greater than the preset critical pressure, it is determined that a new main road turbine operating point needs to be added. This process continues until the outlet pressure corresponding to the newly added main road turbine operating point is less than or equal to the preset critical pressure, at which point the addition of a new main road turbine operating point is stopped.

[0056] In this embodiment, after the set of turbine operating points to be used is determined, the outlet pressure of the final turbine operating point is extracted and compared with the preset critical pressure. When the outlet pressure is less than or equal to the preset critical pressure, there is no need to add a main turbine operating point, and the parameter processing can proceed directly. During the parameter processing, the heat exchanger temperature node needs to be called. The heat exchanger temperature node is the inlet and outlet temperature value of the heat exchanger between each stage in the cryogenic section, which is determined by the inlet and outlet temperatures of the turbine operating point and the heat balance calculation of the heat exchanger. It is the thermal link connecting each stage of the turbine in the refrigeration process parameters. The heat exchanger temperature node and the turbine operating point parameters are input into the parameter processing operation. Parameter processing is the step of summarizing all the scattered turbine operating point parameters, heat exchanger temperature nodes, and parameters before and after the JT valve into a unified dataset. The parameter processing outputs the refrigeration process parameters, which include the number and layout of the turbine expander units, the inlet and outlet temperatures, pressures, and flow rates of each turbine, the temperature nodes of each stage of the heat exchanger, and the parameters of the main turbine and the JT throttling node. When the outlet pressure is greater than the preset critical pressure, the main turbine operating point is added. The main turbine operating points are connected in series after the final turbine stage. Using the supercritical state as the outlet target, the inlet pressure and expansion ratio are calculated back-calculated, and the outlet pressure is compared again with the preset critical pressure. If it is still greater than the preset critical pressure, more main turbine operating points are added. Each time a new main turbine operating point is added, its outlet pressure decreases until the outlet pressure of the latest added main turbine operating point is less than or equal to the preset critical pressure, at which point additions cease. After all additions are completed, all main turbine operating points are added to the set of turbine operating points to be used, and then the parameter processing is performed to output the final refrigeration process parameters.

[0057] The working principle and beneficial effects of this embodiment are as follows: By extracting the outlet pressure of the last-stage turbine operating point in the turbine operating point set, the outlet pressure is compared with a preset critical pressure. If the outlet pressure is less than or equal to the preset critical pressure, the parameters of the inlet and outlet temperatures, pressures, flow rates, and heat exchanger temperature nodes are processed to obtain refrigeration process parameters. If the outlet pressure is greater than the preset critical pressure, it is determined that a main circuit turbine operating point needs to be added. The outlet pressure of the main circuit turbine operating point is compared with the preset critical pressure. If the outlet pressure is greater than the preset critical pressure, the main circuit turbine operating point continues to be added until the outlet pressure of the latest added main circuit turbine operating point is less than or equal to the preset critical pressure, at which point the addition stops. By comparing the outlet pressure with the preset critical pressure, the need for adding a main circuit turbine is automatically determined, ensuring that the pressure before throttling is in the optimal range. By iteratively adding main circuit turbines, the outlet pressure is gradually reduced to below the critical pressure, improving the throttling refrigeration efficiency.

[0058] To achieve the above embodiments, this disclosure also proposes a multi-stage turbine refrigeration cycle design device.

[0059] Figure 5 This is a schematic diagram of a multi-stage turbine refrigeration cycle design device provided in an embodiment of this disclosure. The device 200 can be implemented by software and / or hardware and is generally integrated into an electronic device. Figure 5 As shown, the device 200 includes: an iteration module 201, a recursion module 202, a configuration module 203, and an output module 204, wherein, The iteration module 201 is used to determine the basic boundary conditions according to user requirements and compressor parameters, and to perform iterative optimization of the final stage turbine based on the basic boundary conditions and the preset parameter configuration method to determine the operating point of the final stage turbine. The operating point of the final stage turbine includes the outlet temperature, the inlet temperature and the final stage turbine setting framework. The recursive module 202 is used to calculate the initial compressor flow rate and initial total theoretical work of each stage based on the operating point of the final stage turbine, and proceed to the next stage in the direction of increasing temperature to determine the new turbine operating point. If the power consumption reduction benefit corresponding to the new turbine operating point meets the first preset condition, the module outputs the total number of turbine stages and the total set of turbine operating points. The configuration module 203 is used to configure the heat exchanger of the cryogenic temperature zone turbine section based on the total number of turbine stages and the total turbine operating point set, verify the total turbine operating point set according to the configuration result, and output the turbine operating point set to be used if the verification result meets the second preset condition. The output module 204 is used to compare the outlet pressure of the last stage turbine operating point in the set of turbine operating points to be used with the preset critical pressure, determine the main turbine operating point based on the comparison result, and add the main turbine operating point to the set of turbine operating points to be used to obtain the overall turbine operating point set, and determine and output the refrigeration process parameters based on the overall turbine operating point set.

[0060] The iterative module 201 in the apparatus provided in this disclosure is specifically used for: The first iteration condition is determined based on the aforementioned basic boundary conditions; Based on the first iteration condition and the preset first parameter configuration method, several initial temperatures are assumed and iterated. Based on the preset accuracy condition, the outlet temperature of the final turbine is determined from the iteration results of all initial temperatures. The inlet and outlet pressures of the final stage turbine are determined based on the basic boundary conditions. The final stage turbine configuration framework and the inlet temperature of the final stage turbine are determined by back calculation based on the inlet and outlet pressures of the final stage turbine, the outlet temperature of the final stage turbine and the helium adiabatic index, using the preset second parameter configuration method. The operating point of the final stage turbine is determined by combining the outlet temperature, the final stage turbine configuration, and the inlet temperature.

[0061] The iterative module 201 in the apparatus provided in this disclosure is specifically used for: Based on the first iteration condition and the preset first parameter configuration method, several initial temperatures are assumed. Based on the first iteration condition and the preset Joule-Thomson throttling process, the temperature calculation point corresponding to each initial temperature is determined, and the required mass flow rate of the Joule-Thomson throttling path at the corresponding temperature calculation point is obtained. The total compressor flow rate at the corresponding initial temperature is obtained by summing the mass flow rates at all temperature calculation points corresponding to each initial temperature. Based on all initial temperatures and the corresponding total flow rate of the compressor, a relationship curve is plotted. Based on preset screening conditions, the minimum value is optimized in the relationship curve to determine the candidate outlet temperature. The accuracy of the candidate outlet temperature is determined according to the preset accuracy condition. If the accuracy of the candidate outlet temperature meets the preset accuracy condition, the candidate outlet temperature is output as the outlet temperature of the final stage turbine. If the accuracy of the candidate outlet temperature does not meet the preset accuracy condition, then a second iteration condition is determined based on the basic boundary condition, and a new initial temperature is assumed based on the second iteration condition and the candidate outlet temperature to obtain a new candidate outlet temperature, until a candidate outlet temperature meets the preset accuracy condition, and the candidate outlet temperature is output as the outlet temperature of the final stage turbine.

[0062] The iterative module 201 in the apparatus provided in this disclosure is specifically used for: The ideal inlet temperature of the turbine is calculated based on the inlet and outlet pressures of the final stage turbine, the outlet temperature of the final stage turbine, and the helium adiabatic index. The ideal inlet specific enthalpy is obtained by referring to the preset property table based on the ideal inlet temperature of the turbine and the inlet pressure of the final stage turbine. The inlet and outlet specific enthalpy of the turbine is obtained by referring to the preset property table based on the inlet and outlet pressures and outlet temperature of the final turbine. The ideal specific enthalpy drop is obtained by subtracting the ideal specific enthalpy from the turbine inlet and outlet specific enthalpy. The maximum ideal speed of the expander is then calculated based on the ideal specific enthalpy drop. If either the maximum ideal speed of the expander or the ideal specific enthalpy drop exceeds the preset engineering feasible range for a single-stage turbine, the final-stage turbine is split. Based on the splitting result, the ideal turbine inlet temperature, the maximum ideal speed of the expander, and the ideal specific enthalpy drop are recalculated until both the maximum ideal speed of the expander and the ideal specific enthalpy drop are within the preset engineering feasible range for a single-stage turbine. If so, the splitting result is deemed valid, and a final-stage turbine configuration framework including the number of turbine stages and the ideal specific enthalpy drop is determined based on the splitting result. The polytropic index is determined based on the initial number of turbine stages in the final turbine configuration, and the ideal inlet temperature of the final turbine is calculated based on the polytropic index.

[0063] The apparatus provided in this disclosure, wherein the recursive module 202 is specifically used for: Calculate the initial compressor flow rate of each stage based on the operating point of the final turbine, and sum the initial total theoretical work by summing the flow rates of all initial compressors. The inlet temperature of the last stage turbine operating point is used as the outlet temperature of the new turbine. The inlet temperature of the new turbine and the new turbine setting structure are determined according to the preset second parameter configuration method in the preset parameter configuration method. The operating point of the new turbine is determined based on the outlet temperature of the new turbine, the inlet temperature of the new turbine, and the new turbine configuration. Based on the newly added turbine operating point and the final stage turbine operating point, the flow rate and total theoretical work of each stage compressor are recalculated to obtain the recalculation results. Based on the recalculation results, the power consumption reduction benefit obtained due to the newly added turbine operating point is determined, and the power consumption reduction benefit is compared with the first preset condition. The first preset condition includes a preset percentage threshold and a preset liquid nitrogen temperature; If the power consumption reduction benefit is higher than the preset percentage threshold, the inlet temperature of the new turbine operating point is compared with the preset liquid nitrogen temperature. If the inlet temperature of the new turbine operating point is higher than the preset liquid nitrogen temperature, the stage addition is stopped, and the total number of turbine stages is determined based on the last turbine operating point and the new turbine operating point. If the inlet temperature of the new turbine operating point is lower than the preset liquid nitrogen temperature, the inlet temperature of the new turbine operating point is used as the outlet temperature for continuing to add turbines, and the process is repeated to obtain the new turbine operating points. The power consumption reduction benefit is then recalculated and compared. If the power consumption reduction benefit is lower than the preset percentage threshold, the total number of turbine stages is determined based on the operating point of the final turbine stage and the operating point of the newly added turbine stage. The preset percentage threshold is the percentage decrease in the total theoretical work in the recalculated result relative to the initial total theoretical work; Output the total number of turbine stages and the total set of turbine operating points, wherein the total set of turbine operating points includes all newly added turbine operating points and the operating point of the final turbine stage.

[0064] The configuration module 203 in the apparatus provided in this embodiment is specifically used for: The heat exchangers in the cryogenic temperature zone turbine section are configured based on the total number of turbine stages and the total set of turbine operating points. Based on the turbine parameters corresponding to each turbine operating point in the total turbine operating point set, the minimum heat transfer temperature difference of each heat exchanger in the configuration result is calculated. The total turbine operating point set is verified according to the minimum heat transfer temperature difference. Based on the verification result, heat exchangers that do not meet the second preset condition are determined, and a list of heat exchangers to be adjusted is obtained. Calculate the temperature difference margin based on the minimum heat transfer temperature difference and the second preset condition, determine the correction target value of the list of heat exchangers to be adjusted based on the temperature difference margin, calculate the supplementary operating point based on the correction target value using the preset parameter configuration method, adjust the configuration of the heat exchangers in the cryogenic temperature zone turbine section based on the supplementary operating point, and add the supplementary operating point to the total turbine operating point set. Based on the turbine parameters corresponding to the supplemented total turbine operating point set, the minimum heat transfer temperature difference of each heat exchanger in the configuration adjustment result is calculated. If there are still heat exchangers that do not meet the second preset condition, a second supplement is performed until all heat exchangers meet the second preset condition. The corresponding total turbine operating point set is then output as the turbine operating point set to be used.

[0065] The output module 204 of the apparatus provided in this embodiment is specifically used for: Extract the outlet pressure of the last stage turbine operating point in the set of turbine operating points to be used, compare the outlet pressure with the preset critical pressure, if the outlet pressure is less than or equal to the preset critical pressure, then there is no need to add a main turbine operating point. Then, organize the inlet and outlet temperatures, pressures, flow rates and all heat exchanger temperature nodes of each turbine operating point in the set of turbine operating points to be used to obtain the refrigeration process parameters. If the outlet pressure is greater than the preset critical pressure, it is determined that a new main road turbine operating point needs to be added. The outlet pressure corresponding to the main road turbine operating point is compared with the preset critical pressure. If the outlet pressure is greater than the preset critical pressure, it is determined that a new main road turbine operating point needs to be added. This process continues until the outlet pressure corresponding to the newly added main road turbine operating point is less than or equal to the preset critical pressure, at which point the addition of a new main road turbine operating point is stopped.

[0066] The multi-stage turbine refrigeration cycle design device provided in this disclosure can execute the multi-stage turbine refrigeration cycle design method provided in any embodiment of this disclosure, and has the corresponding functional modules and beneficial effects of the method.

[0067] To implement the above embodiments, this disclosure also proposes a computer program product, including a computer program / instructions, which, when executed by a processor, implements the multi-stage turbine cooling cycle design method described above.

[0068] Figure 6 This is a schematic diagram of the structure of an electronic device provided in an embodiment of the present disclosure.

[0069] The following is a detailed reference. Figure 6 The diagram illustrates a structural schematic suitable for implementing the electronic device in the embodiments of this disclosure. The electronic device in the embodiments of this disclosure may include, but is not limited to, mobile terminals such as mobile phones, laptops, digital broadcast receivers, PDAs (personal digital assistants), PADs (tablet computers), PMPs (portable multimedia players), in-vehicle terminals (e.g., in-vehicle navigation terminals), and fixed terminals such as digital TVs and desktop computers. Figure 6 The electronic device shown is merely an example and should not be construed as limiting the functionality and scope of the embodiments disclosed herein.

[0070] like Figure 6 As shown, the electronic device may include a processor (e.g., a central processing unit, a graphics processing unit, etc.) 301, which can perform various appropriate actions and processes according to a program stored in read-only memory (ROM) 302 or a program loaded from memory 308 into random access memory (RAM) 303. The RAM 303 also stores various programs and data required for the operation of the electronic device. The processor 301, ROM 302, and RAM 303 are interconnected via a bus 304. An input / output (I / O) interface 305 is also connected to the bus 304.

[0071] Typically, the following devices can be connected to I / O interface 305: input devices 306 including, for example, touchscreens, touchpads, keyboards, mice, cameras, microphones, accelerometers, gyroscopes, etc.; output devices 307 including, for example, liquid crystal displays (LCDs), speakers, vibrators, etc.; memory devices 308 including, for example, magnetic tapes, hard disks, etc.; and communication devices 309. Communication device 309 allows electronic devices to communicate wirelessly or wiredly with other devices to exchange data. Although Figure 6Electronic devices with various devices are shown, but it should be understood that it is not required to implement or have all of the devices shown. More or fewer devices may be implemented or have alternatively.

[0072] In particular, according to embodiments of this disclosure, the processes described above with reference to the flowcharts can be implemented as computer software programs. For example, embodiments of this disclosure include a computer program product comprising a computer program carried on a non-transitory computer-readable medium, the computer program containing program code for performing the methods shown in the flowcharts. In such embodiments, the computer program can be downloaded and installed from a network via communication device 309, or installed from memory 308, or installed from ROM 302. When the computer program is executed by processor 301, it performs the functions defined in the multi-stage turbine cooling cycle design method of embodiments of this disclosure.

[0073] It should be noted that the computer-readable medium described in this disclosure can be a computer-readable signal medium or a computer-readable storage medium, or any combination thereof. A computer-readable storage medium can be, for example,—but not limited to—an electrical, magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus, or device, or any combination thereof. More specific examples of a computer-readable storage medium may include, but are not limited to: an electrical connection having one or more wires, a portable computer disk, a hard disk, random access memory (RAM), read-only memory (ROM), erasable programmable read-only memory (EPROM or flash memory), optical fiber, portable compact disk read-only memory (CD-ROM), optical storage device, magnetic storage device, or any suitable combination thereof. In this disclosure, a computer-readable storage medium can be any tangible medium containing or storing a program that can be used by or in conjunction with an instruction execution system, apparatus, or device. In this disclosure, a computer-readable signal medium can include a data signal propagated in baseband or as part of a carrier wave, carrying computer-readable program code. Such propagated data signals can take various forms, including but not limited to electromagnetic signals, optical signals, or any suitable combination thereof. A computer-readable signal medium can be any computer-readable medium other than a computer-readable storage medium, which can send, propagate, or transmit a program for use by or in connection with an instruction execution system, apparatus, or device. The program code contained on the computer-readable medium can be transmitted using any suitable medium, including but not limited to: wires, optical fibers, RF (radio frequency), etc., or any suitable combination thereof.

[0074] In some implementations, clients and servers can communicate using any currently known or future-developed network protocol such as HTTP (Hypertext Transfer Protocol) and can interconnect with digital data communication (e.g., communication networks) of any form or medium. Examples of communication networks include local area networks (“LANs”), wide area networks (“WANs”), the Internet (e.g., the Internet of Things), and peer-to-peer networks (e.g., ad hoc peer-to-peer networks), as well as any currently known or future-developed networks.

[0075] The aforementioned computer-readable medium may be included in the aforementioned electronic device; or it may exist independently and not assembled into the electronic device.

[0076] The aforementioned computer-readable medium carries one or more programs, which, when executed by the electronic device, cause the electronic device to perform the aforementioned multi-stage turbine cooling cycle design method.

[0077] Electronic devices can be programmed with computer program code in one or more programming languages ​​or combinations thereof to perform the operations of this disclosure. These programming languages ​​include, but are not limited to, object-oriented programming languages ​​such as Java, Smalltalk, and C++, as well as conventional procedural programming languages ​​such as "C" or similar languages. The program code can be executed entirely on the user's computer, partially on the user's computer, as a standalone software package, partially on the user's computer and partially on a remote computer, or entirely on a remote computer or server. In cases involving remote computers, the remote computer can be connected to the user's computer via any type of network—including a local area network (LAN) or a wide area network (WAN)—or can be connected to an external computer (e.g., via the Internet using an Internet service provider).

[0078] The flowcharts and block diagrams in the accompanying drawings illustrate the architecture, functionality, and operation of possible implementations of systems, methods, and computer program products according to various embodiments of this disclosure. In this regard, each block in a flowchart or block diagram may represent a module, segment, or portion of code containing one or more executable instructions for implementing a specified logical function. It should also be noted that in some alternative implementations, the functions indicated in the blocks may occur in a different order than those indicated in the drawings. For example, two consecutively indicated blocks may actually be executed substantially in parallel, and they may sometimes be executed in reverse order, depending on the functions involved. It should also be noted that each block in the block diagrams and / or flowcharts, and combinations of blocks in the block diagrams and / or flowcharts, can be implemented using a dedicated hardware-based system that performs the specified function or operation, or using a combination of dedicated hardware and computer instructions.

[0079] The units described in the embodiments of this disclosure can be implemented in software or hardware. The names of the units are not, in some cases, intended to limit the specific unit.

[0080] The functions described above in this document can be performed at least in part by one or more hardware logic components. For example, exemplary types of hardware logic components that can be used, without limitation, include: field-programmable gate arrays (FPGAs), application-specific integrated circuits (ASICs), application-specific standard products (ASSPs), system-on-a-chip (SoCs), complex programmable logic devices (CPLDs), and so on.

[0081] In the context of this disclosure, a machine-readable medium can be a tangible medium that may contain or store a program for use by or in conjunction with an instruction execution system, apparatus, or device. A machine-readable medium can be a machine-readable signal medium or a machine-readable storage medium. A machine-readable medium can be, but is not limited to, electronic, magnetic, optical, electromagnetic, infrared, or semiconductor systems, apparatus, or devices, or any suitable combination of the foregoing. More specific examples of machine-readable storage media include electrical connections based on one or more wires, portable computer disks, hard disks, random access memory (RAM), read-only memory (ROM), erasable programmable read-only memory (EPROM or flash memory), optical fiber, portable compact disk read-only memory (CD-ROM), optical storage devices, magnetic storage devices, or any suitable combination of the foregoing.

[0082] The above description is merely a preferred embodiment of this disclosure and an explanation of the technical principles employed. Those skilled in the art should understand that the scope of this disclosure is not limited to technical solutions formed by specific combinations of the above-described technical features, but should also cover other technical solutions formed by arbitrary combinations of the above-described technical features or their equivalents without departing from the above-described concept. For example, technical solutions formed by substituting the above features with (but not limited to) technical features disclosed in this disclosure that have similar functions.

[0083] Furthermore, while the operations are described in a specific order, this should not be construed as requiring these operations to be performed in the specific order shown or in a sequential order. In certain environments, multitasking and parallel processing may be advantageous. Similarly, while several specific implementation details are included in the above discussion, these should not be construed as limiting the scope of this disclosure. Certain features described in the context of individual embodiments may also be implemented in combination in a single embodiment. Conversely, various features described in the context of a single embodiment may also be implemented individually or in any suitable sub-combination in multiple embodiments.

[0084] Although the subject matter has been described using language specific to structural features and / or methodological logic, it should be understood that the subject matter defined in the appended claims is not necessarily limited to the specific features or actions described above. Rather, the specific features and actions described above are merely illustrative examples of implementing the claims.

Claims

1. A design method for a multi-stage turbine refrigeration cycle, characterized in that, include: Based on user requirements and compressor parameters, basic boundary conditions are determined. Based on the basic boundary conditions and preset parameter configuration method, the final stage turbine is iteratively optimized to determine the operating point of the final stage turbine. The operating point of the final stage turbine includes the outlet temperature, the inlet temperature and the final stage turbine setting framework. Based on the operating point of the final turbine stage, calculate the initial compressor flow rate and initial total theoretical work of each stage, and proceed step by step in the direction of increasing temperature to determine the new turbine operating point. If the power consumption reduction benefit corresponding to the new turbine operating point meets the first preset condition, output the total number of turbine stages and the total set of turbine operating points. The heat exchangers of the turbine section in the cryogenic temperature zone are configured based on the total number of turbine stages and the total set of turbine operating points. The total set of turbine operating points is verified according to the configuration results. If the verification results meet the second preset condition, the set of turbine operating points to be used is output. The outlet pressure of the last-stage turbine operating point in the set of turbine operating points to be used is compared with the preset critical pressure. Based on the comparison result, the main turbine operating point is determined and added to the set of turbine operating points to be used to obtain the overall turbine operating point set. The refrigeration process parameters are determined and output based on the overall turbine operating point set.

2. The method according to claim 1, characterized in that, Based on user requirements and compressor parameters, basic boundary conditions are determined. Then, based on these basic boundary conditions and a preset parameter configuration method, the final-stage turbine is iteratively optimized to determine its operating point, including: The first iteration condition is determined based on the aforementioned basic boundary conditions; Based on the first iteration condition and the preset first parameter configuration method, several initial temperatures are assumed and iterated. Based on the preset accuracy condition, the outlet temperature of the final turbine is determined from the iteration results of all initial temperatures. The inlet and outlet pressures of the final stage turbine are determined based on the basic boundary conditions. The final stage turbine configuration framework and the inlet temperature of the final stage turbine are determined by back calculation based on the inlet and outlet pressures of the final stage turbine, the outlet temperature of the final stage turbine and the helium adiabatic index, using the preset second parameter configuration method. The operating point of the final stage turbine is determined by combining the outlet temperature, the final stage turbine configuration, and the inlet temperature.

3. The method according to claim 2, characterized in that, Based on the first iteration condition and the preset first parameter configuration method, several initial temperatures are assumed and iterated. The outlet temperature of the final turbine is determined from the iteration results of all initial temperatures according to a preset accuracy condition, including: Based on the first iteration condition and the preset first parameter configuration method, several initial temperatures are assumed. Based on the first iteration condition and the preset Joule-Thomson throttling process, the temperature calculation point corresponding to each initial temperature is determined, and the required mass flow rate of the Joule-Thomson throttling path at the corresponding temperature calculation point is obtained. The total compressor flow rate at the corresponding initial temperature is obtained by summing the mass flow rates at all temperature calculation points corresponding to each initial temperature. Based on all initial temperatures and the corresponding total flow rate of the compressor, a relationship curve is plotted. Based on preset screening conditions, the minimum value is optimized in the relationship curve to determine the candidate outlet temperature. The accuracy of the candidate outlet temperature is determined according to the preset accuracy condition. If the accuracy of the candidate outlet temperature meets the preset accuracy condition, the candidate outlet temperature is output as the outlet temperature of the final stage turbine. If the accuracy of the candidate outlet temperature does not meet the preset accuracy condition, then a second iteration condition is determined based on the basic boundary condition, and a new initial temperature is assumed based on the second iteration condition and the candidate outlet temperature to obtain a new candidate outlet temperature, until a candidate outlet temperature meets the preset accuracy condition, and the candidate outlet temperature is output as the outlet temperature of the final stage turbine.

4. The method according to claim 2, characterized in that, The inlet and outlet pressures of the final stage turbine are determined based on the aforementioned basic boundary conditions. Then, based on a preset second parameter configuration method, the final stage turbine setup structure and inlet temperature are determined by inverse calculation using the inlet and outlet pressures of the final stage turbine, the outlet temperature of the final stage turbine, and the helium adiabatic index. This includes: The ideal inlet temperature of the turbine is calculated based on the inlet and outlet pressures of the final stage turbine, the outlet temperature of the final stage turbine, and the helium adiabatic index. The ideal inlet specific enthalpy is obtained by referring to the preset property table based on the ideal inlet temperature of the turbine and the inlet pressure of the final stage turbine. The inlet and outlet specific enthalpy of the turbine is obtained by referring to the preset property table based on the inlet and outlet pressures and outlet temperature of the final turbine. The ideal specific enthalpy drop is obtained by subtracting the ideal specific enthalpy from the turbine inlet and outlet specific enthalpy. The maximum ideal speed of the expander is then calculated based on the ideal specific enthalpy drop. If either the maximum ideal speed of the expander or the ideal specific enthalpy drop exceeds the preset engineering feasible range for a single-stage turbine, the final-stage turbine is split up. Based on the splitting result, the ideal inlet temperature of the turbine, the maximum ideal speed of the expander, and the ideal specific enthalpy drop are recalculated until both the maximum ideal speed of the expander and the ideal specific enthalpy drop are within the preset engineering feasible range for a single-stage turbine. If so, the splitting result is deemed valid, and a final-stage turbine configuration framework including the number of turbine stages and the ideal specific enthalpy drop is determined based on the splitting result. The polytropic index is determined based on the initial number of turbine stages in the final turbine configuration, and the ideal inlet temperature of the final turbine is calculated based on the polytropic index.

5. The method according to claim 2, characterized in that, Based on the operating point of the final turbine stage, the initial compressor flow rate and initial total theoretical work of each stage are calculated. The process is then iterated step-by-step towards increasing temperature to determine new turbine operating points. If the power consumption reduction benefit corresponding to the new turbine operating point satisfies a first preset condition, the total number of turbine stages and the total set of turbine operating points are output, including: Calculate the initial compressor flow rate of each stage based on the operating point of the final turbine, and sum the initial total theoretical work by summing the flow rates of all initial compressors. The inlet temperature of the last stage turbine operating point is used as the outlet temperature of the new turbine. The inlet temperature of the new turbine and the new turbine setting structure are determined according to the preset second parameter configuration method in the preset parameter configuration method. The operating point of the new turbine is determined based on the outlet temperature of the new turbine, the inlet temperature of the new turbine, and the new turbine configuration. Based on the newly added turbine operating point and the final stage turbine operating point, the flow rate and total theoretical work of each stage compressor are recalculated to obtain the recalculation results. Based on the recalculation results, the power consumption reduction benefit obtained due to the newly added turbine operating point is determined, and the power consumption reduction benefit is compared with the first preset condition. The first preset condition includes a preset percentage threshold and a preset liquid nitrogen temperature; If the power consumption reduction benefit is higher than the preset percentage threshold, the inlet temperature of the new turbine operating point is compared with the preset liquid nitrogen temperature. If the inlet temperature of the new turbine operating point is higher than the preset liquid nitrogen temperature, the stage addition is stopped, and the total number of turbine stages is determined based on the last turbine operating point and the new turbine operating point. If the inlet temperature of the new turbine operating point is lower than the preset liquid nitrogen temperature, the inlet temperature of the new turbine operating point is used as the outlet temperature for continuing to add turbines, and the process is repeated to obtain the new turbine operating points. The power consumption reduction benefit is then recalculated and compared. If the power consumption reduction benefit is lower than the preset percentage threshold, the total number of turbine stages is determined based on the operating point of the final turbine stage and the operating point of the newly added turbine stage. The preset percentage threshold is the percentage decrease in the total theoretical work in the recalculated result relative to the initial total theoretical work; Output the total number of turbine stages and the total set of turbine operating points, wherein the total set of turbine operating points includes all newly added turbine operating points and the operating point of the final turbine stage.

6. The method according to claim 1, characterized in that, The heat exchangers in the cryogenic temperature zone turbine section are configured based on the total number of turbine stages and the total turbine operating point set. The total turbine operating point set is then verified according to the configuration results. If the verification result meets a second preset condition, a set of turbine operating points to be used is output, including: The heat exchangers in the cryogenic temperature zone turbine section are configured based on the total number of turbine stages and the total set of turbine operating points. Based on the turbine parameters corresponding to each turbine operating point in the total turbine operating point set, the minimum heat transfer temperature difference of each heat exchanger in the configuration result is calculated. The total turbine operating point set is verified according to the minimum heat transfer temperature difference. Based on the verification result, heat exchangers that do not meet the second preset condition are determined, and a list of heat exchangers to be adjusted is obtained. Calculate the temperature difference margin based on the minimum heat transfer temperature difference and the second preset condition, determine the correction target value of the list of heat exchangers to be adjusted based on the temperature difference margin, calculate the supplementary operating point based on the correction target value using the preset parameter configuration method, adjust the configuration of the heat exchangers in the cryogenic temperature zone turbine section based on the supplementary operating point, and add the supplementary operating point to the total turbine operating point set. Based on the turbine parameters corresponding to the supplemented total turbine operating point set, the minimum heat transfer temperature difference of each heat exchanger in the configuration adjustment result is calculated. If there are still heat exchangers that do not meet the second preset condition, a second supplement is performed until all heat exchangers meet the second preset condition. The corresponding total turbine operating point set is then output as the turbine operating point set to be used.

7. The method according to claim 1, characterized in that, The outlet pressure of the final stage turbine operating point in the set of turbine operating points to be used is compared with the preset critical pressure. Based on the comparison result, the main turbine operating point is determined and added to the set of turbine operating points to be used, thus obtaining the overall turbine operating point set. The refrigeration process parameters are determined and output based on the overall turbine operating point set, including: Extract the outlet pressure of the last stage turbine operating point in the set of turbine operating points to be used, compare the outlet pressure with the preset critical pressure, if the outlet pressure is less than or equal to the preset critical pressure, then there is no need to add a main turbine operating point. Then, organize the inlet and outlet temperatures, pressures, flow rates and all heat exchanger temperature nodes of each turbine operating point in the set of turbine operating points to be used to obtain the refrigeration process parameters. If the outlet pressure is greater than the preset critical pressure, it is determined that a new main road turbine operating point needs to be added. The outlet pressure corresponding to the main road turbine operating point is compared with the preset critical pressure. If the outlet pressure is greater than the preset critical pressure, it is determined that a new main road turbine operating point needs to be added. This process continues until the outlet pressure corresponding to the newly added main road turbine operating point is less than or equal to the preset critical pressure, at which point the addition of a new main road turbine operating point is stopped.

8. A multi-stage turbine refrigeration cycle design device, characterized in that, The device includes: The iteration module is used to determine the basic boundary conditions according to user requirements and compressor parameters, and to perform iterative optimization of the final stage turbine based on the basic boundary conditions and the preset parameter configuration method to determine the operating point of the final stage turbine. The operating point of the final stage turbine includes the outlet temperature, the inlet temperature and the final stage turbine setting framework. The recursive module is used to calculate the initial compressor flow rate and initial total theoretical work of each stage based on the operating point of the final stage turbine, and proceeds to the next stage in the direction of increasing temperature to determine the new turbine operating point. If the power consumption reduction benefit corresponding to the new turbine operating point meets the first preset condition, the module outputs the total number of turbine stages and the total set of turbine operating points. The configuration module is used to configure the heat exchanger of the turbine section in the cryogenic temperature zone based on the total number of turbine stages and the total turbine operating point set, and to verify the total turbine operating point set according to the configuration result. If the verification result meets the second preset condition, the module outputs the turbine operating point set to be used. The output module is used to compare the outlet pressure of the last stage turbine operating point in the set of turbine operating points to be used with the preset critical pressure, determine the main turbine operating point based on the comparison result, and add the main turbine operating point to the set of turbine operating points to be used to obtain the overall turbine operating point set. The refrigeration process parameters are determined and output based on the overall turbine operating point set.

9. An electronic device, characterized in that, include: Memory; processor; as well as Computer programs; The computer program is stored in the memory and configured to be executed by the processor to implement the steps of the method as described in any one of claims 1-7.

10. A computer-readable storage medium, characterized in that, It stores a computer program / instruction thereon, which, when executed by a processor, implements the steps of the method described in any one of claims 1-7.

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